// plugins/directive.js
import Vue from 'vue'

/**
 * 全局注册自定义指令，用于判断当前图片是否能够加载成功，可以加载成功则赋值为img的src属性，否则使用默认图片
 * 在网络慢的时候，加载图片多的时候，可以达到占位图的效果
 * 使用方法：<img src="默认图片.png" v-real-img="真实图片.png">
 */
Vue.directive('real-img', async function (el, binding) {
  //指令名称为：real-img
  let imgURL = binding.value //获取图片地址
  if (imgURL) {
    let exist = await imageIsExist(imgURL)
    if (!exist) {
      el.setAttribute('src', 'https://cdn.toolify.ai/default.webp')
    }
  } else {
    el.setAttribute('src', 'https://cdn.toolify.ai/default.webp')
  }
})
Vue.directive('real-img-gpt', async function (el, binding) {
  //指令名称为：real-img
  let imgURL = binding.value //获取图片地址
  if (imgURL) {
    let exist = await imageIsExist(imgURL)
    if (!exist) {
      el.setAttribute('src', 'https://cdn.toolify.ai/gpt-default.webp')
    }
  } else {
    el.setAttribute('src', 'https://cdn.toolify.ai/gpt-default.webp')
  }
})

Vue.directive('img-error', {
  bind(el, binding) {
    el.addEventListener('error', () => {
      el.src = binding.value
    })
  }
})

/**
 * 检测图片是否存在
 * @param url
 */
let imageIsExist = function (url) {
  return new Promise((resolve) => {
    var img = new Image()
    img.onload = function () {
      if (this.complete == true) {
        resolve(true)
        img = null
      }
    }
    img.onerror = function () {
      resolve(false)
      img = null
    }
    img.src = url
  })
}
